Ignition Systems Flashcards
7 cards from real ASE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Ignition Systems flashcards as text
What defines a coil-on-plug (COP) ignition system?
Answer: A dedicated ignition coil is mounted directly on each individual spark plug
In a COP system, each cylinder has its own coil mounted directly over its spark plug, eliminating all high-voltage spark plug wires and minimizing energy loss.
A weak or intermittent spark condition would most likely be caused by:
Answer: A failing ignition coil with a degraded secondary winding
A failing ignition coil with weakened secondary insulation or poor winding integrity cannot generate sufficient voltage, producing weak or intermittent spark and engine misfires.
What was the purpose of the ballast resistor in older ignition systems?
Answer: To limit primary coil current during normal operation to prevent coil overheating
The ballast resistor dropped voltage to the coil during normal running to prevent thermal damage, while being bypassed during cranking to provide full voltage and a hotter spark.
On a secondary ignition oscilloscope pattern, what does an abnormally HIGH firing line indicate?
Answer: High resistance in the secondary circuit requiring more voltage to fire
A high firing line means extra voltage was needed to jump the spark gap, indicating high resistance from worn plug electrodes, an excessively wide gap, or damaged secondary wiring.
What is the minimum spark duration generally considered necessary for reliable combustion?
Answer: 0.5 milliseconds
A minimum of approximately 0.5 milliseconds (500 microseconds) of spark duration is generally required to reliably ignite the air-fuel mixture, especially under lean or diluted conditions.
Which type of distributor trigger sensor produces a clean digital square wave signal?
Answer: Hall-effect switch sensor
A Hall-effect switch uses a semiconductor element and magnetic shutter to generate a clean digital on/off square wave, compared to the analog sine wave produced by magnetic inductive sensors.
If a MAP sensor fails and reports falsely low vacuum (high load condition) to the PCM, what typically happens to ignition timing?
Answer: Timing retards to prevent knock under the falsely perceived high-load condition
The PCM interprets low manifold vacuum as high engine load and retards timing to protect against knock, resulting in reduced power and poor fuel economy.